The present invention relates to apparatus for correcting both the existing grade and the horizontal alignment of railroad track in accordance with a wire reference system and, in particular, to a mechanism for such an apparatus capable of indicating to an operator both the grade and horizontal alignment of the track being or to be corrected.
It is well known to correct the horizontal alignment of railroad track with the reference point for the aligning machine being provided by one or two tensioned wires which extend generally parallel to the rails for some distance and are referenced to the existing rails. Examples of known arrangements for aligning track in this manner are shown and described in U.S. Pat. Nos. 3,050,015 dated Aug. 21, 1962, and 3,165,838 dated Jan. 19, 1965.
It is also known to correct the grade or level of railroad track with the reference point or plane for the levelling machine, usually one able to tamp the ballast, also being provided by one or two tensioned wires arranged generally parallel to the rails, taken in a vertical plane extending longitudinally of the rails. These levelling wires are also referenced to the existing rails. Examples of known arrangements for levelling track with the use of wires are described in U.S. Pat. Nos. 3,119,346 and dated Jan. 28, 1964 and 3,433,175 dated Mar. 18, 1969.
Also British Pat. No. 1,204,558 dated Dec. 20, 1968 describes a system for observing the horizontal and vertical alignment of a railroad track that employs a single reference wire in combination with horizontal and vertical scale means and an optical arrangement to project a picture of the instantaneous horizontal and vertical alignment of said track. The optical arrangement includes a number of precisely arranged mirrors and lenses. In this system the same wire is used to provide an indication of both the vertical and horizontal alignment of the track whose position is to be corrected. The described system has several disadvantages including its expense and the skill required to construct is. Such a system could also be difficult to maintain and repair and to adjust to local conditions.
Accordingly it is an object of the present invention to provide an indicator mechanism which is practical and inexpensive, can be used in conjunction with an apparatus for correcting the existing grade and horizontal alignment of railroad track, and indicates by means of only a single reference wire both the existing grade and horizontal alignment of the track.
It is a further object to provide an indicator mechanism having a single needle indicator capable of indicating on suitable scales both the existing grade and horizontal alignment of an adjacent section of track.